The world’s population is doing something once thought nearly impossible: it’s starting to fluctuate. Projections suggest global population may peak much sooner than expected—potentially above 10 billion in the 2060s—then begin to shrink. In wealthier countries this shift is already visible. For example, Japan’s population is shrinking by about 100 people every hour. Meanwhile, birth rates have plunged across Europe, the Americas, and East Asia, and the trend is likely to spread to many middle- and low-income countries.
A team led by demographer Andrew Taylor and climate-and-health researcher Supriya Matthew has been studying this worrying pattern.
Just a decade ago, demographers predicted the global population could reach about 12.3 billion—far higher than today’s roughly 8 billion.
For the past 50 years some ecologists tried to protect the environment by advocating population-control strategies. Now we face a very different reality: population growth is slowing without deliberate control measures, and populations in wealthy countries are steadily falling. What would a global population decline—depopulation—mean for the environment?
Depopulation is Already Happening
Experts say depopulation has been underway for decades across much of Europe, North America, and parts of northern Asia. Birth rates in those places have fallen and stayed low for about 70 years. At the same time, rising life expectancy has doubled the number of very elderly people (those over 80) in the last 25 years.
Until recently, China was the world’s most populous country, making up roughly one-sixth of the global population. Now China’s population is declining rapidly, and that decline is expected to accelerate. Some forecasts suggest that by the end of the century China could have only about one-third of its current 1.4 billion people.
Japan could see its population cut roughly in half by the end of the century.
This is called demographic transition. As countries shift from primarily agrarian economies to industrial and service economies, birth rates fall. When low birth rates pair with low mortality, overall population can begin to shrink.
A major factor is that more women pursue education and careers. They’re having children later in life and, on average, having fewer children.
Population decline creates real economic challenges: the working-age population shrinks while the number of elderly people needing support grows.
By 2100, researchers predict only six countries will have birth rates higher than death rates: Samoa, Somalia, Tonga, Niger, Chad, and Tajikistan. In contrast, birth rates in about 97 percent of countries are expected to fall below the replacement level of 2.1 children per woman.
Will Nature Rest When There Are Fewer People?
No — it’s not that simple. For one thing, people consume the most energy between roughly ages 35 and 55. Consumption declines after that, but then rises again after about age 70, partly because older adults often spend more time at home or live alone in larger houses. The large increase in the elderly population this century could offset some of the consumption drops from having fewer people.
Also consider the massive differences in resource use and carbon footprints across countries. Wealthier countries consume far more per person. So as more countries become wealthier and healthier—even if they have fewer children—a growing share of the global population living at higher incomes could push emissions up.
Expect more liberal immigration policies to boost working-age populations in some places. Migration levels have already exceeded earlier projections for 2050.
When people move to developed countries, it can benefit both migrants and host economies economically. But from an ecological perspective, migration can raise per-capita emissions, because higher income and higher emissions are closely linked.
As the planet warms, forced migration—people fleeing war, drought, or other climate disasters—is projected to reach about 216 million over the next 25 years. Where those people resettle could change emission patterns regionally.
In theory, fewer people should reduce pressure on nature. But will it in practice? If we don’t cut emissions and change consumption patterns—especially in wealthy countries—declining population on its own won’t guarantee a healthier environment.
